Sounds like a ground issue. I had to add a ground wire to my gage cluster because when I turned on the headlights the gages would go nuts. The issue was the ground wire had been disconnected by the PO when he installed a after-market radio. I added a ground wire to the gage cluster and no more issues.
Brian - NCM Lifetime Member
73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System
Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"